1. Field of the Invention
The present invention relates generally to the manufacture of nonwoven fabrics and their treatment to impart desired properties. More particularly, it relates to such fabrics that are normally hydrophobic and substantially nonconductive which are desired for applications requiring conductivity and water and/or alcohol repellency. Applications for fabrics with these properties include, but are not limited to, disposable items for surgical room use such as gowns, drapes, table covers and the like. A particular application is in the manufacture of sterilization wrapper used to enclose items to be sterilized and maintain them in a sterilized condition until used. Such nonwovens are manufactured from a wide variety of materials including naturally hydrophobic fibers of synthetic polymers such as polyolefins, polyesters, polyamides, and the like.
2. Description of the Prior Art
The manufacture of nonwoven webs for the above-identified applications is well-known. In addition, it is conventional practice to treat such nonwovens to impart desired properties such as conductivity and water and/or alcohol repellency. For example, U.S. Pat. No. 4,041,203 to Brock and Meitner issued 9 Aug. 1977 describes a nonwoven laminate of a meltblown microfibrous web and a spunbonded web having very desirable attributes for sterilization wrap. The patent describes treatment of such laminates for electrical conductivity and repellency properties with a quaternary ammonium antistatic agent and a high molecular weight cationic fluorocarbon aqueous emulsion fluid repellent. Additional such treatment compositions are described in U.S. Pat. No. 4,115,605 to Hultman and Bergsbaken dated 19 Sep. 1978. This latter patent also discloses benefits of including salts such as lithium chloride in the treatment compositions.
While such treatments have been successful to a significant degree in attaining the intended results, it remains further desired to improve the effectiveness of such treatment and reduce the level of treatment required, all while maintaining or exceeding the conductivity and repellency levels hitherto obtained. In this manner, economy of production as well as product improvements may be obtained.